Proposed Approach: Out-of-hospital trauma triage is a critical component of trauma systems and the primary mechanism for concentrating seriously injured patients in major trauma centers, yet the triage guidelines have never been rigorously validated or subject to formal cost analysis. In this project, we will use a prospective, population-based, out-of-hospital injury cohort of children, adults, and elders to examine the accuracy and cost implications of the field triage guidelines, plus opportunities for improving the triage algorithm. Importance: Data-driven solutions to increase trauma system efficiency, reduce costs, and preserve valuable resources, while still maximizing injury outcomes are desperately needed. Results from this study could have substantive implications for improving the cost-effective regionalization of seriously injured patients. Objectives: The overall goals of this application are to generate unbiased age-specific estimates of decision scheme accuracy (sensitivity and specificity) among a broad, representative injury population and to closely evaluate the cost implications of field triage. Our hypothesis is that the triage guidelines have higher under- and over-triage rates than previously recognized, that triage is heavily influenced by EMS provider judgment, and that there are significant cost implications associated with mis-triage. This proposal has 3 specific aims: Specific Aim 1. Prospectively validate the field triage decision scheme among children, adults, and elders in 2 urban/suburban sites and 1 rural site using a broad out-of-hospital injury cohort. Specific Aim 2. Evaluate the utility of individual triage criteria (including EMS provider judgment) and re-derive the field trauma triage guidelines within pre-specified age strata for children, adults, and elders. Specific Aim 3. Conduct formal cost analyses of the decision scheme, including differences by hospital type and triage criteria, over- and under-triage, and the cost-effectiveness of different strategies for field triage. Study Design: Population-based, observational, consecutive patient prospective cohort. Setting: The study will be conducted in 3 sites: Portland, OR/Vancouver (4 counties);King County, WA;and Josephine County, OR (rural site). Forty-three EMS agencies and 19 acute care hospitals (3 Level I, 1 Level II, 3 Level III, 4 Level IV, and 8 non-designated community hospitals) will be included. Participants: The study will include all persons with a 9-1-1 response and EMS provider primary impression of "trauma," regardless of whether triage guidelines are met, transport destination or outcome. The EMS cohort will include 58,800 injured patients with 10,877 (the primary sample) sampled for hospital outcomes. Outcome Measures: The primary outcome will be "serious" injury (maximum Abbreviated Injury Scale score 3). The secondary outcome will be a composite measure of serious injury or trauma resource use (major operative intervention, interventional radiology, ICU stay e 2 days, transfusion, prolonged ventilation or in- hospital mortality). Costs will be translated using hospital cost-to-charge ratios, plus EMS and physician costs. PUBLIC HEALTH RELEVANCE: Project Narrative The ability to concentrate seriously injured patients in major trauma centers cost-effectively has significant public health implications. Results of this project will address important knowledge gaps in this public health priority, including: the true age-specific accuracy of field trauma triage guidelines in urban, suburban, and rural community settings;potential changes in the triage algorithm to improve accuracy;and the cost implications of field triage.